The impact of increased renewable energy penetration and reduced inertia on the frequency nadir in a multi-area interconnected network based on the peninsula Malaysia national grid

Abstract

The increased adoption of renewable energy sources (RES) has left the power system grid with ever more decreasing inertia. The inertia plays a crucial part in mitigating frequency changes in the power system. Nevertheless, the extent how which the reduction of inertia affects an interconnected power system has not been studied, specifically the frequency nadir parameter. In this research, the effects of increasing RES penetration and the consecutive reduction in inertia have been studied, and their impact on the frequency nadir was investigated. A transfer function model of the power system frequency was developed based on the Malaysian peninsula interconnected grid, consisting of four regions. Four scenarios were tested, each of which focused on a specific region with varying levels of load disturbances and RES penetration levels. A performance metric, $m_{\mathrm{FD}}$_, was proposed to measure the sensitivity of frequency nadir with different contingency levels at varying RE penetration. The scenarios demonstrated the nonlinear relation between the increase of RE and the frequency nadir. Furthermore, the relation of disturbance magnitude and frequency nadir was determined to be linear. The scenarios demonstrated the role of higher inertia regions in mitigating the effects of contingencies propagating to other regions. Moreover, regions with low inertia and higher interconnections showed more resilience when the contingency occurred outside their area. Conversely, they showed a higher risk for the system when the inertia happens within them. The results show the importance of maintaining inertia in high inertia grids and increasing it in lower inertia grids.